1. Field of the Invention
The present invention relates to an engine tool with a small engine like a chainsaw, and more particularly, an engine tool having a devised air cleaner room or airflow path for engine cooling.
2. Description of the Related Art
Engine tools like chainsaws for cutting a shaft of a tree or a branch thereof are generally driven by a small engine. In general, because a user cuts a branch above his/her head or climbs the tree while holding the chainsaw, the chainsaw is small and light-weighted so that the user can easily lift up the chainsaw by one hand. The chainsaw also has a handle so that the user can easily hold the chainsaw. In order to miniaturize the chainsaw, various devises are made in arrangement of an engine, an exhaust pipe, a saw chain part, and the like, and in attachment of each equipment to a housing. According to a chainsaw disclosed in Unexamined Japanese Patent Application KOKAI Publication No. S61-160201, a cylinder of an engine is arranged inside a main body casing, and an air cleaner room is arranged at the front side of the main body casing. Such a chainsaw is configured in such a way that the main body casing has a compact height in the vertical direction. Moreover, external air is sucked directly into the air cleaner room through communicating holes provided above the air cleaner room.
Regarding letting in of external air into an air cleaner room, according to the technology disclosed in Unexamined Japanese Utility Model Application KOKAI Publication No. H03-78963, external air is sucked through an opening formed in a rear face of a chainsaw and an openable/closable opening formed in a retention wall relative to an engine. Air warmed up as flowing around a cylinder of the engine flows into the air cleaner room. Accordingly, even if an external temperature is cold like winter, the chainsaw is maintained in a good operation condition.
According to recent chainsaws, an engine is retained in an integrally-molded housing, and a saw chain part or the like is attached to the housing. The housing is formed of plastic for weight saving. Accordingly, the plastic-made housing has inferior rigidity of a material itself and the strength thereof in comparison with a metallic housing, and the heat dissipation characteristics are also poor.